McMaster-Carr has a large selection of all types and shapes of
industrial felt.  There is also an excellent reference section that
lists the different grades and characteristics.  It is more than
anyone needs to know about felt!  The web site is mcmaster.com.
Just search for 'felt'.

As an added note, I have found it possible to dye their bleached
white felt with plain old 'RIT' dye that can be found in grocery
stores etc.  I recently wanted some purple felt to replace a muffler
strip (the one that drops down in front of the hammers).  I ordered
a piece of 1/8 x 2" wool felt from McMaster (it is sold by the foot)
and dyed it to the color of choice.

Regards, Larry Emmons